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'3T3 Docbc :7c::. 50-416 50-417 Minsinsippi Pocor & Liaht Co.
A21: !!r. !!. L. Sta plcy Vlec President - Production P. O. Dox 16 0 Jcekson, Micoicoippi 3?205 Centlenen:
'?c have revic ead your res oncen to our rcouests for cdlitional inforna-tion, dated ?tay 12, 1973 cnd July 19, 1973. Lnaed en eur reviev of your reapences, va find th.t sona re93onses vill have tu be nunplcmented with addition:1 infernation.
In addition, vc have cctcblichad certain Ecq-ulatory requirencato in rcrard to the design of the ern':nin ent tehich vill have to bn renolved prior to concludin;; out review.
Identificatien of this need for additional infornation and a Stocenant of Ray,uhtory requira :nto are set forth in Enclocuros 1 and 2 respectively.
To mintain our licensine review schedule, va vill netd a co:pletely au-
"mte response to the requent for additional info =atto1 and to the S*.r.tr..a t of ter;ulatory ?.ocuirenents by ::cve:ber 12, 1973. Ple'.co inform us eithin 7 days c! ct reenipt of thin letter of your cenfirmatico of the above ochedule or the cate you will be able to ceet.
If you cannot eest our specified dato or if your reply is not fully responsive to our requeste.1: 1.,
hichly liholy that the overall echedule for co:pleting the licensing re.vfci ter this project vill have to ba extended.
Since ranscirmneut of the ctaff's efforts will require. completion of the new ausinn ent prior to returninq to this proj:.ct, the t.=ount of extension vill most likely be greater then tha extent of delay in ycur recponse.
The identifying nunbers used in the enclosed Requent for Additional Infert2tica f ollow the. T attern establiched in our previous requests for additional i'derut-tion. L'here appropriate, reference is made to the original questien conce to which your response was made. Yout respense to these addftional quentivne r.nf requiresents cay be e.sde either by incorporatint: the infornatica provie d for other naclear power plants by reference, or you may auend your application by nuhitting revised pages and supplements.
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Pleano contact un if you desire additional di::cussion or clarifiention of the catorial requested.
Sincerely, i
c.eri rim: ty V:n A. t4:: t Voss A. tloore, Assistant Dircetor for Boilinst U&tcr P.cactors Directorate of Licensing Pnclosures:
1.
Ecque:c for Additionni Infor:ation 2.
Statencnt of Regulctory Rcquirenents cc: 1:r. Robert C. Travis Attorn2y Distribution:
!!1sc, Carte, Child, Docket Files (50-416/417)
Steen & Carnway AF.C PDR P. O. rox 651 Local PDR Jachcoa,!!iscissippi B'n'R-1 File V. A. Moore
'!r. Uillira E. Carner J. Hendrie Route 4 D. Eisenhut Scottaboro, Alabama 35768 L. Powell, OGC R0 (3)
Connor & Knotts G. Owsley suite 1050 H. Maigret (w/5 extras) 1747 Pcnncylvania Avenue,11. W.
R. Cudlin Washington, D. C.
20006 TR Branch Chiefs BWR Branch Chiefs lir. Elisha C. Poole ACRS (16)
P. O. Box 308 Greenville, Alabama 36037
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4 ENCLOSURE 1 RE0UEST FOR ADDITT0"AL INFOTtATION GRAND GULF NUCLFAR STATI0", UNITS 1 AND 2 DOCKET NOS. 50-416/417 6.2.43 As you indicated in our meeting concerning containment design matters on August 10, 1973, the Mark III vent clearing model has been revised. The new model is described in the second Mark III test program progress report, NEDM 10976,' transmitted by letter from }T&L on July 31, 1973, and is shown to correlate with small scale Mark III test data. However, in the first progress report, NEDM 10848, the originci vent clearing model was also shown to agree with small scale Mark III test data.
Considering the above:
a.
Describe the differencen between the vent clearing models; b.
Discuse the effect that each variation in the model has on drywell differential pressure; c.
Explain the significance of each vent clearing model being able to adequately predict vent clearing phenomenon as seen in the small scale Mark III tests; d.
Specify the values of the loss coefficients and describe how r.
they are determined.
(The control volume equations used to model the horizontal vents indicate that "turning" loss co-efficients are applied to the vent velocity terms.)
e.
Specify.the value of the effective length, L*, used in the control volume equations.
6.2.44 Specify the values of the individual loss coefficients used in the i
vent flow model and describe how these coefficients will be experi-mentally verified on the full scale Mark III test facility.
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(Ref.: Item 6.2.3) 6.2.45 Provide sensitivity curves, similar to your response to Item 6.2.3, of drywell differential pressure as a function of reactor vessel level swell time following a main steam line break.
6.2.46-Provide an updated response to Item 6.2.6 concerning the potential input of feedwater energy to the containment following a loss-of-coolant accident.
Specify the total amount of feedwater energy which could be added to the containment and justify your statement that this additional energy would not result in higher long term con-tainment pressures.
6.2.47 As requested by Item 6.2.9 (c), provide a detailed description of the modeling of the drywell depressurization which occurs at about 600 seconds post-LOCA (PSAR Figure 6.2-9).
Specifically discuss and provide analyses of the manner in which the spray effectiveness of the break flow is determined and provide a table of break flow and enthalpy as a function of time.
6.2.48 Supplement your response to Item 6.2.20, regarding Category II air lines within primary containment, as follows:
a.
Specify the amount of service air which could be released to primary containment following failure of the Category II service air lines; b.
Discuss the principles of operation of the alarm system which would indicate to the operator than an instrument air line had broken within primary containment; c.
Specify the amount of instrument air which could be released to primary containment following failure of the Category II
lines and before manual isolation of the system; and-d.
Discuss the effect that the volu=en of air in (a) and (c) would have on containment peak pressure.
6.2.49 Provide the design criteria which have been cpplied for postulated breaks in high energy, unguarded pipe lines located within pri. nary containment but outside the drywell. Also, provide details of the analyses performed for each break, e.g., break sizes and location, blowdown rate, lape times for detection systems, contain ent pres-sure, etc., which demonstrate that the amount of blowdown fluid released to the containment is within accept'able linits.
6.2.50 As requested in Item 6.2.29 (b), specify the nur.ber of hydrogen re-circulation valves which will operate as automatic vacuum relief valves.
6.2.51 Your response to Item 6.2.30 (d) does not consider pcsitive drywell te containment differential pressures. Discuss the espability of the recirculation valves to open if a differential pressure, corre-sponding to the submergence of the first row of vents, existed across the valve disk.
i 6.2.52 Your response to Item 6.2.31 stater..that none of the pipes within the drywell are in enclosed subconpartments. However, from PSAR j
figures 5.5.10a and 5.1-4, it appears that the RHR head spray line may be located in a restricted volume within the drywell. Therefore, provide a drawing which illustrates the routing of the RHR head spray line and discuss the consequences of a rupture in the line between the reactor vescel and the inbeard check valve.
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6.2.53 Your response to Item 6.2.34, concerning post-accident sup-pression pool water levels, does not appear accurate in the following respects and should be revised:
Figure R.6.2.34-1 indicates that the containment pool a.
overflows into the drywell following drywell depressurization.
If the vacuum breakers are operable this should not occur.
b.
Figure R.6.2.34-1 shown the water level in the drywell above the top of the weir wall (at about 5 minutes) and the water level in the annulus at the top of the wall. This does not.
appear possible.
The final level of water in the containment and vent annulus c.
is !.ndicated to be at the first row of vents. Hosever, your response to Item 6.2.32 states that the vents should be sub-merged two feet following pool drawdown.
6.2.54 With respect to your analyses of subcompartments, describe the analytical methods that were used to 1.etermine the jet impingement forces.
6.2.55 The containment external design differential pressure is indicated to be 3 psi in the PSAR (p. R6.2.38-1).
Describe and provide de-tails of the analyses of the types of transients which could result in negative pressures within prieary containment. Justify the margins which are allowed between the maximum calculated negative pressures and the design value. From this evaluation and other factors deemed pertinent, discuss the need for a containment vacuum breaker system.
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6.2.56 Our review of the isolation valve' arrangements described in PSAR Section 6.2.4 and Table 6.2.7 indicates that a number of primary containment penetrations do not explicity conform to General Design Criteria (GDC) 55-57.
Briefly, GDC 55-57 require that two isolation valves be provided, one inside and one outside the primary containment; that these valves close automatically; and that the valves fail, on loss of power, in the position of greater safety.
Cersidering the above, provide a list of all primary containment penetrations which do not meet these criteria and in each case provide a discussion and an analys'is which demonstrate that exception to the GDC is justified.
If in some cases this i
justification is already provided in the PSAR, then a specific page I
reference will be an acceptable response.
6.2.57 Provide the following information'with respect to the Standby Gas e
Treatment System (SGTS) and secondary containment:
4 a.
Elevation drawings which clearly indicate the boundaries of the 1
A list of any high energy lines which are within secondary containment; c.
The failure modes of valves in the SGTS; and d.
Justification for assuming that both trains of the SGTS are available for drawdown of the secondary containment pressure
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to -1/4" w.g., following an accident (Ref.: PSAR p.6.4-3).
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6.2.58 Section 6.2.1.3.5 of the PSAR references Appendix A of NEDO 10329, "Loss-of-Coolant Accident and Emergency Core Cooling Models for General Electric Boiling Water Reactors", for the reactor vessel level swell model used in the main steam line break analysis. However, since the containment design basis break is indicated to be the main steam line, the manner in which the topical report model ia appiind to containment analysis requires clarification as follows:
a.
Reference the specific parts of Appendix A which are applicable o the level swell associated with a main steam line blowdown analysis; b.
List any conservative assumptions which were incorporated in the model for containment analysis purposes; c.
Provide results of the level swell times that are calculated by the model considering various reactor operating conditions su'ch as full power, hot staniby etc.; and d.
List the input parameters used in the above analyses.
6.2.59 Specify the pump heat rate input (Ltu/sec) to the containment follow-ing a loss-of-coolant accident and j.ustify its exclusion from the long-term containment response analysis described in PSAR Section 6.2.1.3.7.
6.2.60 Your response to Item 6.2.9 and discussions in the Regulatory staff's 4
meeting with you on August 10, 1973, indicate that for containment mass and energy input rates, the primary system is modeled as a single volume at the average primary system enthalpy. Justify that 4
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this represents a conservative assumption for containment analysis purposes considering that the reefrculation loop conditions display a significant (20 Btu /lbm) degree of sub-cooling.
Provide a blowdown tabic (mass and energy input rates versus time) and containment response profiles for a recir-culation line break assuming that the primary system is modeled as one volume, vith the total mass inventory at operating pressure and at the average enthalpy of the recirculation loops.
6.2.61 Provide an analysis of containment and drywell pressure response to a main steam line or recirculation line b'reak (whichever is the worst case) assuming that the react 6r is at hot standby and 9
the suppression pool is at an elevated temperature corresponding to the hot standby condition at the time of the break.
6.2.62 As indicated in response to Item 6.2.33, the vent flow medel as described in GE Topical Report, NEDM-10320, "The General Electric Pressure Suppression Containment Analytical Model" was used to preduct the critical flow threshold for the Mark III vent system.
This method is based on the principle that only the vapor region determines the sonic.haracteristics of the two-phase mixture.
Using this assumption, ideal gas relationships have been used to predict sonic flow. There are, however, experimental and analytical data within the literature that inlii: ate the liquid phase does lower the sonic chot. 6 eristics of the mixture below the value that would j
be calculated for only the vapor phase. Regulatory staf f members discussed wit'a General Electric specific references indicating this l
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l trend during a meeting at San Jose en September 20 and 20, 1973.
As a result, justify the applicability of the ideal gas-choked flow model in light of the contradictory data within the field, which includes the RELAP prediction comparisons of both the semiscale r,
i and Battelle blowdown experiments.
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b ENCLOSURE 2 r -:
I STATEMENT OF REGULATORY RigUIREMENTS GRAND GULF NUCLEAR STATION, t NITS 1 AND 2 DOCKET NO3. 50-416 AND 50-417 Item 6.2.1-The Grand Gulf Nuclear Station Mark III Containment should have the capability to operate recirculation mixing of hydrogen at any time af ter 10 minutes following a loss-of-coolant accident.
This assures a reasonable design basis to accommodate the metal-water reaction extent indicated in Regulatory Guide 1.7.
The applicant has provided an analysis in Amendment 11 which accept-ably demonstrates this capability for Grand Gulf.
6.2.2 You were requested, in Item 6.2.9(c), to justify the post-bloudown drywell depressurization phase of the containment response.
Your response was not adequate.
Item 6.2.47 in Enclosure 1 of this letter, also addresses this concern.
If this phenomenon cannot be adequately demonstrated, some positive means will need to be provided to reduce the drywell pressure and ensure the return of air from the containment to the drywell.
6.2.3 You are proposing a drywell design differential pressure which is 15% greater than the peak calculated differential pressure. We be-lieve that a minimum of a 30% margin should be applied and that the final margin will be a function of the conservatism of the pressure response analysis which is under review.
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